Refrigerated containers and dry van trailers are extensively used internationally. The lower portions of the container typically experience far more wear and abuse than the upper portions, however the roofs are occasionally damaged due to improper loading of cargo or by a fork lift operator's carelessness.
Trailers have typically been constructed as open top containers for bulk materials or as closed top containers for dry goods. Open top cargo containers allow for easy loading of bulk goods, such as corn and other food stuffs, but are not sufficiently watertight to carry goods that may be damaged by exposure to moisture. Conversely, closed top over the road containers provide their cargo with excellent protection from the elements, but are more difficult to load.